The Toyota 86 and Subaru BRZ may be two of the most desirable cars on the market, but some owners claim to be experiencing engine issues with the sporty Japanese twin coupes.

A report from Automotive News states the Toyota and Subaru two-doors ? which were co-developed and are powered by the same 2.0-litre ?boxer? engine ? are experiencing rough engine idle symptoms and occasional stalling.

According to the article, Subaru and Toyota representatives have stated the issue is related to a software problem. It states the car?s ECU (engine control unit) is an adaptive computer that picks up on how the owner drives the car in the first 100 miles (161 kilometres), and sets the engine to perform accordingly. The ECU may then pick up if the car is being driven outside of these tolerances, and send an error code, causing the engine to idle roughly or stall.

Toyota says the problem is not mechanical, and that the ECU?s software will need to be re-mapped (or ?re-flashed? in car jargon) if it has less than 100 miles on the clock. It says that if the odometer reading is higher, the ECU should be replaced.

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?This is not a mileage-dependent condition,? Subaru spokesman Dominick Infante is quoted as saying. ?No replacement of the ECU is needed at any mileage to rectify the issue. The ECU re-flash is the fix. There is not a defect concerning the ECU.?

Drive is still awaiting a response from Toyota Australia and Subaru Australia.

International enthusiast sites such as FT86club.com are openly discussing the problem, with more than 100 registered complaints about rough idle issues including one forum member who says their car has been ?in the shop? for three weeks with parts including the engine?s oil control valve and variable valve timing cam gear requiring replacement. In a number of cases, those who have complained and had their ECU re-flashed have stated the rough-idle problem is still occurring.

Australian owners have also taken to the internet to discuss the engine problem. The gt86.com.au forum has a thread dedicated to the problem, with several users explaining how their cars have been affected.

?Well in my case if the car sits idle for 1-2 minutes it is likely to conk out and you can feel the car shaking,? writes user tisb0b. ?This can usually be negated to an extent by having my foot on the accelerator and brake at the same time keeping it around 1.5k rpms [sic].?

?For me it happens intermittently, mostly shortly after the car is in neutral, idling,? writes forum user keen as. ?It is very rough idling, revs varying 100-400, coughing (mis-firing [sic]), car shaking (embarassing [sic] at the lights), stalled once. The engine smooths with light throttle pressure to keep around 1.5k rpms [sic]. If I didn't do this to smooth the engine, I guess the CEL [Check Engine Light] will come back on again.?

Another, apparently unrelated issue raised by some BRZ and 86 owners is that of a ?chirping? sound from the car?s fuel pump. Described as similar to the sound of a cricket, the sound is reported to start occurring once the car reaches 300 miles (482km), and while it is not considered problematic, several users on the subarubrzforum.com site have indicated they are opting for a fix at their dealership.